1. Technical Field
The invention relates to an apparatus for determining and improving proprioceptive ability.
2. Background Information
Proprioception relates to the sensation of body movements and awareness of posture, enabling the body to orient itself in space. Sensory clues associated with proprioception originate from within the body from sensory nerve terminals found in muscle joints, tendons and the inner ear which are sensitive to body position and movement. Proprioceptive ability is a learned behavior.
A device for measuring the ability of a person to balance is presented in U.S. Pat. No. 4,122,840 to Tsuchiya, et al. In the '840 patent, a device is described wherein a person to be tested steps on a pair of foot steps and a plurality of body load detectors sense the body load of the person as applied to the footsteps. An arithmetic circuit receives the body load signals and provides difference signals which are displayed so that the person being tested can observe them. That is, the person being tested "sees" body load distribution patterns on a display and adjusts his body balance as a function thereof and in response thereto. A key feature of the device set forth in the '840 patent is the use of visual cues to enable a person to develop balance. The visual cues appear on a monitor that the person being tested reacts to.
Desjardines, et al. in U.S. Pat. No. 4,850,588 describe a balancing apparatus for surfboards. The balancing apparatus generally comprises a platform, upon which a person can stand, mounted on top of a support post by means of a main universal joint. The main universal joint allows the platform to tilt or pivot about the support post. The apparatus includes means connected between the platform and the post for tilting the platform on the post about first and second axes orthogonal to and passing through the center axis of the main universal joint. Thus, the tilting means provides a side-to-side yawing motion to the surfboard on the post about the first axis and also provides a fore and aft pitching motion to the surfboard on the post about the second axis. The tilting means can be operated to simultaneously combine the yawing and pitching motions. There is, however, no means on the device to start and stop a timing device when the board is in or out of balance. Moreover, there is no means for adjusting the limits within which a board can be considered to be in balance. Thus, it is difficult to determine accurately whether or not a person's balance is improving with extended use of the apparatus. That is, the device does not provide a quantitative method for measuring proprioceptive ability.
Wallace, et al. in U.S. Pat. No. 4,463,946, the contents of which patent is incorporated herein by reference, describe a fitness evaluation apparatus for quantitatively measuring a person's physical fitness, agility and reaction time. The device measures the ability to maintain and regain balance and includes a balance beam on which the test subject stands. The apparatus includes a counter for counting the number of times balance is lost during a test cycle and a timer for timing the duration of imbalances during the test cycle. Thus, the Wallace, et al. apparatus provides a means for measuring a person's ability to balance over a test time period which includes the number of times a person went out of balance and the duration of the periods that were out of balance. The disadvantage of the Wallace, et al. device is that it employs a balance beam which enables a person to balance in only a single plane. That is, there is a single axis through a balance beam around which axis a balancing board rotates which permits only a pitching motion or a side-to-side yawing motion but not both simultaneously. The balanced board can only rotate in the plane perpendicular to the axis of the balance beam. Thus, the balancing platform does not provide a 360.degree. dynamic plate which must be held in balance but rather only a movable beam that rotates in a single plane.
An interesting device for simulating flight and weightlessness is described in U.S. Pat. No. 3,859,736 to Hill, et al. The device, referred to as a kinesthetic control simulator, has a flat base which rests upon a support structure having a lower spherical surface for rotation. Columns support the platform above the support structure at a desired location with respect to the center of curvature of the spherical surface. A handrail is provided at approximately the elevation of the hips of the operator above the platform with a ring attached to the support structure which may be used to limit the angle of tilt. The device resembles a telephone booth mounted upon the flat surface of a section sliced from a sphere. The balance position is achieved by pneumatic or thrust means depending upon the embodiment. The device does not respond to changes in the body's center of gravity to maintain a balanced position, but rather the manipulation of pneumatic or thrusting devices are employed to maintain balance. Moreover, there is no means for quantitatively measuring the amount of time spent out of balance during a test period.
With each of the foregoing devices, there is shown to be a general lack of features which permit a person to measure their proprioceptive skills quantitatively. Mason, et al. in U.S. Pat. No. 5,112,045 describe a device for diagnosing and rehabilitating bodily injuries. The device comprises a rigid platform resting atop an elastically deformable support member much like an inner tube. The patient stands on the platform and balances or performs other exercises on the platform which require the patient to work against the instability of the support member. The performance of the exercises enables diagnosis and rehabilitation of any kind of anesthetic impairment which the patient may be experiencing. This device like the previous devices does not provide means for determining how long a portion of a test period is spent out of balance and what portion is spent in balance and therefore is not useful for quantitatively evaluating and developing proprioceptive ability.
Jain, et at. in U.S. Pat. No. 5,209,240 describes a device for registering and recording induced imbalance in a human subject. A horizontal platform is adapted for controlled linear displacement in a horizontal plane to induce imbalance. Imbalance and response can be detected and recorded by means of electric contact shoes or other means. This device differs from the previous devices in that rather than measuring a person's ability to maintain a balanced position wherein the user has complete control over the position of the device, the Jain, et at. device induces an imbalance that the user must respond to. The Jain device does not, however, provide simultaneous motion in three dimensions. The displacements of the platform are limited to a controlled displacement in a horizontal plane. That is, the plane of the platform itself. It is the sort of motion that makes one lurch and stumble about until they regain their motion, much like stepping on an escalator or the motion one experiences during an earthquake or stepping onto a treadmill belt.
In view of the foregoing devices and their limitations, there is seen to be a need for an apparatus which enables the user to balance with simultaneous motion about two perpendicular axes to bring a platform into balance and to quantitate the amount of time the board is in and out of balance during a particular test period.